The principal aim of Project 1 is to test the hypothesis that individual differences in behaviorally evoked cardiovascular reactivity are associated positively with atherosclerosis and indices of left ventricular enlargement among previously untreated hypertensives. Among the specific objectives of this project are to determine: (a) whether variability in the magnitude and patterning of hemodynamic adjustments induced by behavioral stimuli (stress) are associated with extent of carotid artery atherosclerosis and/or evidence of increased left ventricular mass among hypertensive individuals; (b) whether such relationships vary in nature of magnitude between African-American and Caucasian hypertensive; and (c) whether individual differences in cardiovascular reactivity mediated relationships of psychosocial factors (e.g., anger/hostility; social support) with atherosclerosis or left ventricular mass among Caucasian and African-American individuals. We propose to recruit 400 borderline and mild hypertensive men, defined by systolic blood pressure between 140 and 180 mm Hg. Data to be collected on each patient include: (a) cardiovascular responses to a battery of behavioral (cognitive, psychomotor and interpersonal) challenges; (b) ultrasound measurements of carotid artery disease; (c) echocardiographic measurements of left ventricular structure and function, as well as noninvasive evaluations of vascular compliance; (d) psychosocial factors previously implicated in hypertension or coronary disease; and (3) several known or putative risk factors for cardiovascular disease (e.g., fasting insulin, serum lipid concentrations, ambulatory blood pressure, the first systematic study of the relationship of cardiovascular reactivity to both atherosclerosis and left ventricular mass in a biracial hypertensive sample uncomplicated by prior treatment. Secondarily, this study will provide important new information regarding racial differences in ventricular morphology, vascular compliance, extracranial carotid artery disease and hemodynamic reactions to stress, as well as the relationship of these parameters to psychosocial factors of potential significance for cardiovascular disease.